RU2259429C2 - Electrolyte and a method of a nickel plating of made out of aluminum and its alloys - Google Patents

Abstract

FIELD: radio industry; instrumentation technologies; aircraft industry and in other fields of a national economy; galvanotechnics.

SUBSTANCE: the invention is pertaining to the field of galvanotechnics and may be used in the radio industry, instrumentation technologies, aircraft industry and in other fields of a national economy for anticorrosive protection of aluminum and its alloys and to add it special properties. The electrolyte contains(in g/l): nickel sulfamate - 300-350, a boric acid - 25-35, sodium fluoride - 1.5-2.5, alkyl sulfate - 0.05-1.0, pH of electrolyte - 2.5-3.5. The method includes an organic solvent cleaning, pickling treatment, a water flushing in hot running water, a water flushing in cold running water, clarification, a water flushing in cold running water, deposition of nickeliferous coating from the above indicated electrolyte at the temperature of 60-65°C, at current density of 0.3-9.0 A/dm², a water flushing in hot running water, a water flushing in cold running water, drying. The technical result: production of ductile deposits of a nickel directly on aluminum and its alloys.

EFFECT: the invention ensures production of ductile deposits of a nickel directly on aluminum and its alloys.

2 cl, 3 ex

Description

The invention relates to electrolytes and methods for nickel plating of products from aluminum and its alloys. It can be used in the radio engineering industry, instrument making, aircraft industry and in other areas of the national economy for the corrosion protection of aluminum and its alloys and giving them special properties.

Nickel plating electrolyte for anticorrosive protection of aluminum alloys is known in modern technology [OST 107.460092.001-86 "Metallic and nonmetallic inorganic coatings. Typical technological processes], consisting of g / l:

Nickel sulfate 180-230 Sodium Sulfate 40-60 Boric acid 23-28 Sodium Chloride 1-3 Potassium Sulphate 1-3 Sodium Fluoride 1-3 PH 4-5 Temperature ° C 40-50 The current density, A / DM ² 1-2

The method of applying a nickel coating includes the following operations: degreasing with an organic solvent, etching in an alkali solution, washing in hot running water, washing in cold running water, clarification in a solution of nitric acid, washing in cold running water, zinc treatment or preliminary nickel plating, washing in cold running water, electrochemical nickel plating, washing in hot running water, washing in cold running water, drying.

The closest in technical essence to the proposed nickel plating electrolyte ["Electroplating" G.A.Sadakov, Moscow, "Mechanical Engineering", 1987, p. 78] is an electrolyte based on sulfamic nickel in the following ratio of components:

Nickel sulfamic acid 300-340 Boric acid 27-30 Nickel chloride 3.3-30 Sodium Lauryl Sulfate 0.1 pH of the composition 3,5-4,2 temperature, ° С 28-60 The current density, A / DM ² 2-25

A nickel coating on aluminum and its alloys is applied over the copper sublayer, over the anode film, over the zincate film, after cathodic activation in a 10% solution of hydrofluoric acid.

A disadvantage of the known electrolytes and the method of nickel plating of products from aluminum and its alloys is the impossibility of applying a nickel coating directly to aluminum and its alloys.

An object of the invention is to provide an electrolyte and a method for nickel plating products from aluminum and its alloys to obtain ductile nickel deposits directly on aluminum and its alloys.

The solution to the problem is achieved in that the electrolyte for nickel plating of aluminum and its alloys consists of nickel sulfamic acid, boric acid, a surfactant. New features of the claimed electrolyte is its fluoride content in the following ratio of components, g / l:

Nickel sulfamic acid (TU 6-09-2350-78) 300-350 Boric acid (GOST 18704-78) 25-35 Sodium fluoride (GOST 4463-76) 1.5-2.5 Alkyl Sulphates 0.05-1.0 pH of the composition 2.5-3.5 temperature, ° С 60-65 The current density, A / DM ² 0.3-9.0

The method of applying a nickel coating to aluminum and its alloys is based on degreasing with an organic solvent, etching, washing in hot running water, washing in cold running water, clarification, washing in cold running water, electrochemical nickel coating, washing in hot running water, washing in cold running water, drying. The novelty of the proposed method for applying a nickel coating to aluminum and its alloys consists in the fact that the deposition of an electrochemical nickel coating is made from an electrolyte composition, g / l:

Nickel sulfamic acid 300-350 Boric acid 25-35 Sodium Fluoride 1.5-2.5 Alkyl Sulphates 0.05-1.0 pH of the composition 2.5-3.5 Temperature ° C 60-65 The current density, A / DM ² 0.3-9.0

Alkyl sulfates are anionic surfactants, the general formula is ROSO ₃ M, where R is the primary or secondary monovalent saturated aliphatic radical, which include, for example, methyl, ethyl, propyl, isopropyl, etc .; M - Na, K, NH ₄ (Chemical Encyclopedia, Moscow, ed. Sov. Encyclopedia, 1983, p. 24).

Example 1

Nickel coating was applied on aluminum alloy AMC according to the following technology:

1. AMC alloy surface preparation:

- degreasing in an organic solvent, for example, alcohol-gasoline mixture;

- etching in solution, for example, NaOH - (50 ... 100) g / l;

- flushing in hot running water;

- flushing in cold running water;

- clarification in solution, for example, HNO ₃ - (300 ... 400) g / l;

- flushing in cold running water.

2. Application of a nickel coating from an electrolyte composition, g / l:

Nickel sulfamic acid 300 Boric acid 25 Sodium Fluoride 1,5 Alkyl Sulphates 0.05 pH of the composition 2,5 Temperature ° C 60 The current density, A / DM ² 0.3

3. Rinsing in running hot water.

4. Rinsing in cold running water.

5. Drying.

AMC aluminum alloy coating is even and continuous. Pitting, swelling and flaking are not observed. The coating is low-stress; after deformation, peeling of the coating was not detected.

Example 2

Nickel coatings were applied to the AMG aluminum alloy using the following technology:

1. Preparation of the surface of the alloy example 1.

2. Application of a nickel coating from an electrolyte composition, g / l:

Nickel sulfamic acid 325 Boric acid thirty Sodium Fluoride 2.0 Alkyl Sulphates 0.5 pH of the composition 3.0 Temperature ° C 62.5 The current density, A / DM ² 2,5

3. Rinsing in running hot water.

4. Rinsing in cold running water.

5. Drying.

AMC aluminum alloy coating is even and continuous. Pitting, swelling and flaking are not observed. The coating is low-stress; after deformation, peeling of the coating was not detected.

Example 3

Nickel coating was applied to the aluminum alloy D-16 using the following technology:

1. Surface preparation example 1.

2. Application of a nickel coating from an electrolyte composition, g / l:

Nickel sulfamic acid 350 Boric acid 35 Sodium Fluoride 2,5 Alkyl Sulphates 1,0 pH of the composition 3,5 Temperature ° C 65 The current density, A / DM ² 9.0

3. Rinsing in running hot water.

4. Rinsing in cold running water.

5. Drying.

AMC aluminum alloy coating is even and continuous. Pitting, swelling and flaking are not observed. The coating is low-stress; after deformation, peeling of the coating was not detected.

Claims (2)

1. Electrolyte for nickel plating of products from aluminum and its alloys, including nickel sulfamic acid, boric acid, a surfactant, characterized in that it additionally contains sodium fluoride, and as a surfactant, alkyl sulfates, in the following ratio of components, g / l: Nickel sulfamic acid 300-350 Boric acid 25-35 Sodium Fluoride 1.5-2.5 Alkyl Sulphates 0.05-1.0 electrolyte pH 2.5-3.5 2. A method for nickel plating products from aluminum and its alloys, including degreasing with an organic solvent, etching, washing in hot running water, washing in cold running water, clarification, washing in cold running water, electrochemical nickel coating, washing in hot running water, washing in cold running water, drying, characterized in that the deposition of an electrochemical nickel coating is made from the electrolyte according to claim 1 at a temperature of 60-65 ° C and a current density of 0.3-9.0 A / dm ² .